In order to realize the potential of fiber optic transmission of light signals, some form of switching mechanism must be provided for moving light signals from one fiber to another. In principle, mechanical switches have a number of advantages over other forms of optical switches for applications in which switching speed is not important. Mechanical switches offer low insertion losses, a high degree of immunity against backscattering of light from the switch back down the input fiber, low cross-talk, and insensitivity to the wavelength of the light being switched.
Prior mechanical switches, however, have been too costly to achieve full market acceptance. Typically, these switches operate by moving an input fiber relative to a plurality of output fibers. The simplest schemes utilize a “butt-coupling” scheme in which the input fiber is aligned with one of a plurality of output fibers using a motor. The output fibers are usually fixed to a carrier and have ends cut at an angle to prevent reflections from the ends generating reflections that propagate back down the input fiber. The angle is typically 6 to 10 degrees.
To provide acceptable insertion losses, the ends of the fiber in a butt-couple switch must be separated by an extremely small distance. This tolerance is difficult to achieve in switches having a large number of output fibers. Hence, butt-coupling schemes, while appearing simple, are in reality extremely difficult and challenging to implement in large fan-out switches.
Accordingly, there is a long-felt yet unsolved need in the art for a mechanical switch that selectively couples light from two input fibers to a selected two of a plurality of output optical fibers, without using lenses or beam collimators.